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Commit 321488cf authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Greg Kroah-Hartman
Browse files

cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all() 

commit 43626dade36fa74d3329046f4ae2d7fdefe401c6 upstream.

syzbot is hitting percpu_rwsem_assert_held(&cpu_hotplug_lock) warning at
cpuset_attach() [1], for commit 4f7e7236435ca0ab ("cgroup: Fix
threadgroup_rwsem <-> cpus_read_lock() deadlock") missed that
cpuset_attach() is also called from cgroup_attach_task_all().
Add cpus_read_lock() like what cgroup_procs_write_start() does.

Link: https://syzkaller.appspot.com/bug?extid=29d3a3b4d86c8136ad9e

 [1]
Reported-by: default avatarsyzbot <syzbot+29d3a3b4d86c8136ad9e@syzkaller.appspotmail.com>
Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: 4f7e7236435ca0ab ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock")
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarCai Xinchen <caixinchen1@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e4463009

kernel/cgroup/cgroup-v1.c

+3 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/delayacct.h>

#include <linux/pid_namespace.h>

#include <linux/cgroupstats.h>

#include <linux/cpu.h>



#include <trace/events/cgroup.h>
@@ -55,6 +56,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) 
	int retval = 0;



	mutex_lock(&cgroup_mutex);

	get_online_cpus();

	percpu_down_write(&cgroup_threadgroup_rwsem);

	for_each_root(root) {

		struct cgroup *from_cgrp;
@@ -71,6 +73,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) 
			break;

	}

	percpu_up_write(&cgroup_threadgroup_rwsem);

	put_online_cpus();

	mutex_unlock(&cgroup_mutex);



	return retval;